Electric gauge



E. F. GALLAUDE ELECTRIC GAUGE. APPLICATIONHLEDSEPLZS,1917.'

Patented Aug. 1, 1922.

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4 bww A TTORNEYS.

UNITED STATES PATENT OFFICE.

' EDSON F. GALLAUDET, 0F PROVIDENCE, RHODE ISLAND.

'ennemie GAUGE.

1 Specification of Letters Patent.

Patented Aug. 1, 1922.

Application led September 26, 1917.y Serial No. 193,258.

operator of an aeroplane or automobile, for` example, can readily read the amount of gasolene remaining in the tank of his englne, although it vmay be found equally avallable for many other purposes.

It is especially important that the pilot of an aeroplane should be able to known at all times the quantity of gasoleneleft in the tank of his engine, and, with the increaslng size and complexity of aircraft, it has become essential that the dials of all instru.- ments shall be assembled on an instrument board in front of the operator where they can be read easily and quickly.

Gasole e gauges Aare almost universally made wi h a oat inside of the tank, connected t6 an indicator'outside in such manner.' that .thez float, controlled by the level of the gasolene, operates the indicator,` which -may be mounted upon. a conveniently located, instrument board whenever a Sulliciently flexible connection with the float is permitted. But, while an electrical connection through insulated wires has the advantage of maximum' flexibility, electric gauges have heretofore been avoided from fear that sparks caused by changesgin connections" in some part of the circuit near the tank might ignite the gasolene vapor and cause an explosion.

The object of the present invention is to provide an electric gauge in which sparking is impossible, making'it safe for use on gasolene tanks and especially on the gasolene tanks of aeroplanes.

My improved gauge consists, of av suitable source of `electric energy, a meter, and in circuit ltherewith a variable resistance which is controlled by the tank float, the principle of operation being based upon the law that the drop in potential in is proportional to the essentially,

an electrlc circuit reslstance thereln.

able brush which, without ever the circuit' at this at all times,

In its preferred 4form I employ a battery of two dry cells, connected together in rseries and having a volts, a volt meteradaptedto register the entire electromotlve force of the battery, a coil of line resistance wire which is wound 'on a spool of insulating material mounted within the gasolene tank in such manner that a brush, moving with the float and wide enough to span two or three turns ofthe wlre coil as the Ho'at is raised or lowered by changes in the level of the gasolene.y Thel battery, conveniently located anywhere, is vgrounded onone side and on the other is connected through a push button switch both with one terminal of the volt meter, which with the .push button is mounted' on total capacity of Say three of the coll'at once, will sweep over the the instrumentboard, andy with the lowerf end of theresistance coil the up er end of which is grounded., The second terminal 'of the volt meter is connected with the movbreaking point, varies the amount of the resistance 1n series with the volt meter in direct proportion to the level of the gasolene in the tank. Consequently, whenever the connections are closed bypressing back the push button, the volt meter will receive and its pointer will indicate an electromotive force roportioned directly height of the goat, thereby showlng the quantity of gasolene in the tank.

thus secure lthe advantage of flexible electric connections, while the voltage employed is so low and the resistance in the circuit is so hi h that the volume of the current is not -sufgcient to form a spark. Furthermore, the mechanism of the gauge is so arranged that the entire circuit is closed except at the push button switch on the mstrument board by which to thethe connections can be made long enough 4 to read the meter and then left open to prevent the rapid exhaustion of the battery, so that no sparking can occur within or near the" tank even thou h the current were strong enough to profuce it.

lThe construction and device will be fully understood by reference 4to the accompanying drawings, in which- Flgure 1 is a vlew showingA diagrammati- .cally the principal 'parts of the gauge and their electrical connections, and 1 2 a vertical section on ,the line 2 v2 of the operation of the Y terminal of the volt soldered at 8 Ato ,of the coil the wire,

` tween the inner ends of `the spool, the contact a horizontal section on the line 2, through the casingin which and Fig. 3, 3 3 of Fig.

the r`resistance; coil, float arm, and contact able material, is open on one side'and is provided with a flanged edge 2 by which it is connected totheside of the 4tank around `an opening in its wall.` A spool 3 of non-conducting material about which iscoiled the resistance wire 4, woundpreferably in a shallow helical roove by which the turns of the wire will' e held in place, rests at its lower end upon an annular vshoulder y5 on the bottom of the casing and-is secured in position therein by the shouldered lower end of a screw plug 6', also of insulating material, which is inserted in a threaded opening 7 provided therefor in The upper end of the resistance coil is the wall of the casing, by whichit is grounded. From the lower end after being passed through an opening 9. in is carried ,upwardlytherein and soldered at 10` to a screwv bolt 11 which extends up through the insulating plug and serves as a binding post forv the lower end ofthe coil, the two nuts 12'and 13 serving'the first to secure the bolt in place within the plug and the second to clamp thereto the end of an outside wire. 'A second screw bolt 14, simi- 'larly provided with two nuts 15 and 16, is

secured horizontally in 17 17 set in openings in the sides of an outward projection 18 in the casing and directly opposite the vertical center and somewhat to one side of the resistance coil. Upon this screw bolt as a pivot is mounted, be-

x the two bushings, the fioat arm 19 which, extending past the s ool on one side and out through the open si the c-asing, carries attached to its free end the tank oat 20 (see Fig. 1) and opposite brush 21, this brush bearing lightly against the bare sides of the wire of the resistance coil and being in electrical connection with the pivot bolt as a binding post.

The two-cell battery 22, grounded on one side preferably on the casing 1, is on the other side connected by the wire 23 'to one terminal of the push button switch 24-and through that switch by lthe Wire 25 vto one meter 26 and by the wire 27, attached to the screw bolt 11, to the lower end of the resistance coil. The other terminal of the volt meter is connected by the wire 28 to the pivot the float arm to the contact brush.

Thus, if the tank is full, the

insulating. bushings brush will bear against the upper endof the resistance coil, and the volt meter, whenever the top of the casing..

the' side of the spool,

cof U bolt 14 and by it and' float will beA 1n lts mostelevated position, the contact theconnections are closed switch, will receive the tive force ot'` the batter volts, or ,full tank. gimilarly, when the tank is empty, the lloat will be at the bottom of the tank and hold the contact brush against the lower end of the resistance coil, and accordingly the volt meter, both of its terminals being connected to the coil at the same point with no diii'erence of potential between them, will read zero, or tank empty. And at any intermediate level of gasolene, the brushwill make Contact with theresistance coil at a proportionally intermediate point in its length and theYA volt meter will receivean electromotive force in proportion to the distance of such contact point from the lower end of the coil 'and will indicate a corresponding proportion of the full three volts or ofthe gasolene to the full capacity of the tank. A

Owing to the fact that the contact brush moves through the arc of a circle while the coil, for convenience of manufacture, is wound on a straight spool, the scale ofthe volt meter should be specially calibrated, as shown. In ythe specific gauge` illustrated, the te'n lines which represent each a ten per cent change in the level of the gasolene correspond to the following readings on the ordinary scale of the/volt meter, viz: .38 .66

.92 1.10 1.32 1.54 1.74; 2.00 2.30 3.00 volts.

The electric gauge constructed as shown at the push button entire electromoand register three 'and described is applicable to any tank con-l taining an oily Huid, like gasolene, kerosene, lubricating oil, etc., which will not short circuit the resistance coil, and can be used on automobiles, trucks, on aeroplanes. If it is 'desired to use the gauge on tanks containing other fluids, the construction will have to be lchanged in ways obvious to those skilled in the art.

While I have shown and specifically described only that embodiment of my invention which I now consider to be best adapted for the purpose inview, it will, of course, be understood that the construction can be variously modified in its several details, within the scope of the appended claims, without departing from the spirit or sacrificing the advantages of the invention.-

What I claim as new, and desire to secure by Letters Patent, is-

1. In an electric gauge, afloat-controlled rheostat comprising as elements thereof a spool of non-conducting material, a resistance coil wound upon the spool and secured 1n position thereon, a float, and a brush mounted to move with the float to sweep one side of the resistancecoil and of a width to bridge two adjoining turns thereof.

2. In an electric gauge, a Heat-controlled rheostat comprising as elements thereof a spool of non-conducting material with a.l helical groove in its outer surface, a resistand boats, as well as the float arm adapted to sweep the side' of coi and extending outwardly through the i the resistance as the float rises and falls and vopen side of the casing, and a brush carried of a width to bridge two adjoining turns by the float arm in contact with the coil and thereof. electrically connected -to 'a circuit terminal 3.- A float-controlled rheostat comprislng outside the casing.

in combinatlon a casing to receive fluids, a 5. A float-controlled rheostat comprising spool of non-conducting materlal vertically incombinatlon a casing open along one side within the casing.to swing vertically in coiled about the spool in the helical groove proximity to one side of the coil, and a brush and electrically connected at one end to a carried by the float arm in contact with the circuit termlnal mounted in and insulated vcoil and electrically connected to a second from a wall of the casingfa float carrying termlnal also mounted in and insulated from an arm pivotally mounted to swing vertia wall of the casing; cally in proximity to a side of the resistance 4. A 'float-controlled rheostat comprising coil and extending outwardly through the in combination'a casing open along one side open side of the casing, and a brush carried and adapted to be attached to the wall of a by the float arm in contact with the resisttank in communication with the interior ance coil and electrically connected to a secthereof, a resistance coil mounted vertically ondcircuitterminal mounted in and insuwithin the casing. and electrically connected lated from a wall of the casing. at one end to the casing and at the other end EDISON F. GALLAUDET 

